Email: [email protected]
Phone: +91 93135 43530
Address: 133/1 Ground, Mansuri Block, Opp. Dudheshwar Water Tank, Ahmedabad-380004, Gujarat, India
Krishna Industries — O-Ring Supplier, Ahmedabad Since 2017
Bulk supplier of O-Rings in NBR (Nitrile), EPDM, PTFE (Teflon), Viton (FKM), and Silicone — DIN 3771 Metric and AS568 Inch sizes — 70 Shore A standard — ID 1mm to 500mm — valve seals, hydraulic, pneumatic, pharma, food, chemical applications.
GST Invoice · MTC Available · MOQ 100 Nos · PAN India Dispatch from Ahmedabad
An O-Ring is a circular elastomeric or PTFE seal — torus-shaped with a round cross section — compressed between two mating surfaces to prevent leakage of liquid or gas. O-rings are the most widely used seals in Indian industrial equipment — valves, pumps, hydraulic cylinders, pneumatic actuators, heat exchangers, and process equipment — because they are economical, available in multiple materials, and can seal practically all media when the correct material is selected.
Krishna Industries (KELOR), based in Ahmedabad, Gujarat, supplies O-rings in all five primary materials — NBR, EPDM, PTFE (solid and encapsulated), Viton (FKM), and Silicone — in DIN 3771 metric (ID x CS in mm) and AS568 inch (dash number) sizes — 70 Shore A standard hardness (60 and 80 Shore A on request) — for valve maintenance, hydraulic and pneumatic equipment, pharma and food GMP processing, and general industrial sealing. GST invoice. MOQ 100 Nos. Pan India dispatch from Ahmedabad.
⚠️ Critical: Using the wrong O-ring material causes failure within days to weeks. NBR in steam service, EPDM in mineral oil, PTFE in a standard rubber groove — all cause immediate leakage. Use the material selection guide below before ordering. If unsure, WhatsApp your fluid, temperature, and pressure for material recommendation within 2 hours.
Select Your O-Ring Material — Complete Range
NBR (Nitrile) O-Ring Oil · Fuel · Hydraulic · Compressed Air · -40°C to +120°C · Most popular
EPDM O-Ring Hot Water · Steam · HVAC · Biocide Water · -40°C to +150°C
PTFE O-Ring Solid PTFE & Encapsulated · Chemical · Pharma · FDA · -200°C to +260°C
Viton (FKM) O-Ring High Temp · Aggressive Chemical · Fuel · -20°C to +200°C
Silicone O-Ring Food · Pharma · Medical · -60°C to +230°C · FDA Grade
O-Ring Kits — Mixed Sizes NBR / Viton / EPDM · Maintenance & MRO assortment kits
O-Ring Material Selection Guide — India’s Most Common Industrial Applications
Highest selling O-ring materials in India — ranked by volume. NBR is #1 by far for industrial MRO. EPDM is #1 for HVAC and water treatment. Viton is #1 for high temperature and chemical. PTFE for aggressive chemical and pharma GMP. Silicone for food, pharma, and medical.
| Material | Temperature | ✅ Use For | ❌ Do NOT Use For | Colour | India Ranking |
|---|---|---|---|---|---|
| NBR (Nitrile / Buna-N) | -40°C to +120°C | ✅ Mineral oil, hydraulic oil, diesel, petrol, LPG, compressed air (oil-free & lubricated), ambient water, salt water — most common Indian industrial MRO O-ring — valve stem seals, hydraulic cylinders, pneumatic actuators, ball valve body seals | Steam, hot water above 80°C, ozone, ketones, esters, chlorinated solvents | Black | 🥇 #1 — highest volume |
| EPDM (Ethylene Propylene) | -40°C to +150°C | ✅ Hot water above 80°C, steam to 150°C, HVAC chilled & hot water, biocide-treated cooling water, ozone, UV, potable water — butterfly valve shaft seals, HVAC solenoid valve seals, heat exchanger gaskets | Mineral oil, hydraulic oil, diesel, petrol — EPDM swells immediately in hydrocarbon service | Black | 🥈 #2 — HVAC & water |
| Viton / FKM (Fluoroelastomer) | -20°C to +200°C | ✅ High temperature above 120°C, aggressive chemical (acid, alkali, solvent), fuel at elevated temperature, ozone — where NBR or EPDM temperature or chemical resistance is exceeded — refinery, chemical plant, hot oil service | Ketones (acetone, MEK), esters, amines, low temperature below -20°C | Brown / Black | 🥉 #3 — chemical & high temp |
| PTFE (Teflon) — Solid or Encapsulated | -200°C to +260°C (solid) | ✅ Universal chemical resistance — concentrated acids (HCl, H₂SO₄, HNO₃), strong alkali (NaOH), oxidising chemicals — pharma GMP product contact (FDA 21 CFR) — cryogenic to very high temperature — ball valve seat backup seals | Dynamic high-speed sealing without special groove design — PTFE has no elasticity, requires higher squeeze than rubber | White | #4 — pharma & chemical |
| Silicone (VMQ) | -60°C to +230°C | ✅ Food and beverage GMP (FDA 21 CFR), pharmaceutical product contact, medical device, oven and baking equipment, cosmetics — excellent low-temperature flexibility — tasteless and odourless — wide temperature range | Dynamic high-pressure sealing (low tensile strength), mineral oil & petroleum products (silicone has moderate oil resistance only) | Red / White / Translucent | #5 — food & pharma |
How to Specify O-Ring Size — DIN 3771 Metric (ID × CS)
A DIN 3771 metric O-ring is specified by two dimensions: Inner Diameter (ID) and Cross Section cord diameter (CS) — both in millimetres. Written as ID × CS. For example, 50 × 3.5 means 50mm inner diameter and 3.5mm cord cross section.
To measure a replacement O-ring: Remove the old O-ring. Use a vernier calliper — measure inner diameter across the inside of the ring (ID), then measure the cord thickness (CS). Specify these two numbers. Do not estimate — 0.5mm error causes leakage or improper seating.
| Cross Section (CS) | Typical ID Range | Common Valve / Equipment Application |
|---|---|---|
| 1.5mm | 1.8mm – 25mm | Instrument valves, solenoid valves, small bore fittings |
| 2.0mm | 3.0mm – 40mm | Small ball valve stem seal, solenoid valve body |
| 2.5mm | 6.0mm – 50mm | DN50–DN80 butterfly valve shaft O-ring, pneumatic cylinder |
| 3.0mm | 10mm – 100mm | DN80–DN150 BFV shaft seal, gate valve bonnet seal |
| 3.5mm | 20mm – 200mm | DN150–DN300 BFV shaft and body joint seal, 3-piece ball valve body |
| 4.0mm | 30mm – 300mm | Large valve body seal, actuator piston seal |
| 5.0mm | 50mm – 400mm | Large bore valve flange seal, heat exchanger plate gasket |
| 6.0mm | 75mm – 500mm | Very large bore valve body seal, large actuator |
Industries & Applications
🔧 Valve Maintenance
Butterfly valve shaft seals (EPDM), ball valve stem and body seals (NBR), gate valve bonnet seals (NBR/EPDM), check valve seals.
⚙️ Hydraulic Equipment
Hydraulic cylinder piston and rod seals (NBR 70–80 Shore A), pump body seals, manifold block seals, hydraulic fitting seals.
💨 Pneumatic Actuators
Pneumatic cylinder piston O-rings (NBR for oil-lubricated air, EPDM for oil-free air), valve actuator body seals, solenoid valve pilot seals.
❄️ HVAC Systems
Butterfly valve shaft seals (EPDM), chilled water pump seals, AHU solenoid valve body seals, heat exchanger connection seals.
💊 Pharmaceutical GMP
Reactor vessel drain valve seals (PTFE/Viton FDA grade), WFI pump seals, sterile process equipment body seals — SS316L compatible.
🍽️ Food Processing
Silicone or PTFE O-rings — FDA 21 CFR compliant — mixing tank drain seals, pump body seals, filling machine seals — tasteless, odourless.
⚗️ Chemical Plants
Viton or PTFE for aggressive chemical, acid, alkali service. NBR for hydrocarbon chemical. EPDM for aqueous chemical. Material selection critical.
🏗️ EPC & MRO Stores
Bulk O-ring supply for plant MRO — assortment kits in NBR, Viton, EPDM across DIN 3771 sizes — single GST invoice, Pan India delivery.
Which O-Ring Material for Your Valve — Quick Reference
| Valve / Equipment | O-Ring Position | Standard Service | Correct Material |
|---|---|---|---|
| CI Butterfly Valve — HVAC chilled water | Disc shaft seal (top & bottom) | Biocide-treated cooling water | ✅ EPDM 70 Shore A |
| CI Butterfly Valve — raw water / irrigation | Disc shaft seal | Raw water, sewage | ✅ NBR 70 Shore A |
| 3-Piece Ball Valve — WCB/SS316 — oil service | Body joint O-ring and stem seal | Mineral oil, hydraulic oil | ✅ NBR 70 Shore A |
| 3-Piece Ball Valve — steam service above 120°C | Body joint O-ring and stem seal | Steam / hot condensate | ✅ Viton (FKM) 70 Shore A |
| Pneumatic Actuator — oil-lubricated instrument air | Cylinder piston and rod seal | Compressed air with oil mist | ✅ NBR 70 Shore A |
| Hydraulic Cylinder — mineral oil HLP | Piston and rod dynamic seal | Mineral oil — high pressure above 100 bar | ✅ NBR 80 Shore A |
| Gate/Globe Valve — hot water above 80°C | Bonnet seal / gland packing O-ring | Hot water, steam condensate | ✅ EPDM or Viton |
| Pharma Reactor Bottom Valve — product contact | Seat backup and stem seal | API / active pharmaceutical ingredient | ✅ PTFE (FDA grade) or Viton FDA |
| Food Processing Pump — product contact | Pump body and impeller seal | Food grade — GMP | ✅ Silicone FDA or PTFE FDA |
| Chemical Plant — HCl / H₂SO₄ service | Valve body and stem seal | Concentrated acid | ✅ PTFE encapsulated or Viton |
Why Plant Maintenance Teams and MRO Buyers Choose Krishna Industries
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All 5 Materials — One Supplier
NBR, EPDM, PTFE, Viton, Silicone — DIN 3771 metric and AS568 inch — single GST invoice for your complete MRO O-ring order.
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Any Size — Custom Dimensions
Standard DIN 3771 sizes in stock. Custom ID × CS dimensions manufactured to your drawing or sample. WhatsApp dimensions for pricing.
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B2B Supplier Since 2017
Sourced from verified Indian manufacturers. Consistent Shore A hardness and material grade across batches — critical for valve assemblers.
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GST Invoice & MTC
100% GST invoice (GSTIN: 24AKLPP6499B1ZT) with every order. Material test certificate — FDA 21 CFR compliance certificate for pharma and food grades on request.
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PAN India Dispatch
Dispatching from Ahmedabad via Professional Courier / VRL to all states — typically 2–5 working days transit after dispatch.
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2-Hour Quote
WhatsApp material, ID × CS size, Shore A hardness, and quantity. Pricing within 2 hours. Mon–Sat 9 AM–7 PM IST.
Need O-Rings for Valve Maintenance or MRO Stock?
WhatsApp material (NBR / EPDM / PTFE / Viton / Silicone), size (ID × CS in mm or AS568 dash number), Shore A hardness, and quantity. We reply within 2 hours.
📲 WhatsApp for O-Ring PricingSupply Coverage — PAN India
Krishna Industries dispatches O-rings from our Ahmedabad warehouse to all major industrial cities: Surat, Vadodara, Rajkot, Ankleshwar, Vapi, Dahej (Gujarat) · Mumbai, Pune, Nashik, Nagpur (Maharashtra) · Chennai, Coimbatore, Bengaluru, Hyderabad (South India) · Delhi, Noida, Gurugram (NCR) · Kolkata, Jaipur, Indore, Lucknow and all other states.
Frequently Asked Questions
How do I identify whether my existing O-ring is NBR or EPDM — they look the same?
Both NBR and EPDM are typically black and look identical. The only reliable field identification method is to apply a drop of mineral oil or diesel to the O-ring surface and leave for 60 seconds — NBR is unaffected while EPDM swells visibly (slight surface bloating). This test damages the O-ring so discard it after. The safest approach is to check the valve or equipment manufacturer’s parts manual — it lists the O-ring material for each position. Alternatively WhatsApp us the equipment make and model number for material confirmation before ordering.
What is the DIN 3771 O-ring size system — how do I read ID × CS?
DIN 3771 is the German metric O-ring standard used across Indian industrial equipment. Every O-ring is specified by two dimensions: ID (Inner Diameter) and CS (Cross Section cord diameter), both in millimetres, written as ID × CS. For example 40 × 3.5 means a 40mm inner diameter ring with a 3.5mm cord. To measure: place the O-ring flat, measure across the inside hole for ID, then measure the rubber cord thickness for CS, using a vernier calliper. Always measure with the O-ring relaxed — stretched or compressed O-rings give wrong dimensions. AS568 is the American inch standard — specified by dash number (e.g. -214). We supply both DIN 3771 metric and AS568 inch sizes.
Which O-ring material is best for butterfly valve shaft seals in HVAC?
Specify EPDM 70 Shore A for all HVAC butterfly valve shaft seals — chilled water, condenser water, and hot water circuits. EPDM resists the biocide treatment chemicals (chlorine-based and bromine-based) used in Indian HVAC cooling water systems, handles the temperature range of HVAC systems (-40°C to +120°C), and resists ozone. The shaft seal O-ring must match the main valve seat material — an EPDM-seated butterfly valve requires EPDM shaft O-rings. Fitting NBR shaft O-rings in an EPDM seat BFV serving biocide-treated HVAC cooling water causes premature shaft seal failure within one operating season.
When should I use Viton instead of NBR for an O-ring?
Specify Viton (FKM) when the service exceeds NBR’s temperature limit (above 120°C continuous), or when the fluid is an aggressive chemical, solvent, or acid that attacks NBR. Viton handles to +200°C — standard for hot oil valves, refinery process equipment, and chemical plant valves in solvents that degrade NBR. Viton also resists ozone and UV — standard for outdoor equipment where NBR cracks in ozone atmosphere within 2–3 years. Viton costs significantly more than NBR — use it only when NBR’s limits are genuinely exceeded. For standard ambient temperature oil and hydraulic service, NBR is the correct and more economical choice.
Is PTFE O-ring a direct replacement for a rubber O-ring of the same size?
No — a solid PTFE O-ring cannot be directly installed in a groove designed for a rubber O-ring. Rubber O-rings need 15–25% diametral squeeze and self-energise under fluid pressure. PTFE has no elasticity — it needs 20–30% squeeze and does not self-energise. If a solid PTFE O-ring is fitted in a standard rubber groove, there is inadequate squeeze and the joint leaks immediately. PTFE encapsulated O-rings (elastomeric core with PTFE jacket) can often be used in standard rubber O-ring grooves because the elastomeric core provides the springback and self-energisation. Always specify the groove design or send a groove drawing when ordering solid PTFE O-rings. For direct replacement, specify PTFE encapsulated type.
What is the MOQ and what documentation is provided?
MOQ is 10 Nos for standard DIN 3771 metric sizes in NBR, EPDM, and Silicone. MOQ is 100 Nos for EPDM bulk supply (valve assembler and OEM quantities). MOQ is 10 Nos for PTFE and Viton. For custom sizes (ID × CS not in DIN 3771 standard range), MOQ is 1 No for large sizes. Every order includes GST invoice (GSTIN: 24AKLPP6499B1ZT). FDA 21 CFR compliance certificate for food and pharma grade Silicone, PTFE, and Viton available on request. Material test certificate (MTC) for PTFE grades confirming FDA compliance available for pharma GMP documentation. WhatsApp material, ID × CS dimensions, Shore A, and quantity for pricing within 2 hours.